From 86b9df01ee698246665847f7dcc52351ce83fecb Mon Sep 17 00:00:00 2001
From: Matthias Melcher <github@matthiasm.com>
Date: Wed, 26 Nov 2025 14:07:34 +0100
Subject: Add initial log support for sliders (#1232).

Works for all slider types.
Adds tick marks to "nice slider".
Defaults to linear if min or max is zero.
There is room for improvement for drawing the tick marks.
---
 FL/Fl_Slider.H | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 2 deletions(-)

(limited to 'FL/Fl_Slider.H')

diff --git a/FL/Fl_Slider.H b/FL/Fl_Slider.H
index d1ced6731..8a70e4e85 100644
--- a/FL/Fl_Slider.H
+++ b/FL/Fl_Slider.H
@@ -24,7 +24,8 @@
 #include "Fl_Valuator.H"
 #endif
 
-// values for type(), lowest bit indicate horizontal:
+#include <FL/Fl_Rect.H>
+
 #define FL_VERT_SLIDER          0
 #define FL_HOR_SLIDER           1
 #define FL_VERT_FILL_SLIDER     2
@@ -58,10 +59,39 @@
 */
 class FL_EXPORT Fl_Slider : public Fl_Valuator {
 
+public:
+
+  /// Bitset for tick mark positions for Fl_Nice_Slider.
+  /// \see Fl_Slider::ticks(), Fl_Slider::ticks(Tick_Position)
+  typedef enum : uchar {
+    TICKS_NONE = 0x00,    ///< draw no ticks
+    TICKS_BELOW = 0x01,   ///< draw ticks below a horizontal slider
+    TICKS_ABOVE = 0x02,   ///< draw ticks above a horizontal slider
+    TICKS_LEFT = 0x01,    ///< draw ticks to the left of a vertical slider
+    TICKS_RIGHT = 0x02    ///< draw ticks to the right of a vertical slider
+    // Later: LABEL : label the first, middle, and last tick with its value
+    // Later: FRACTIONAL : make a half ticks a bit shorter, and quarter ticks even shorter
+    // Later: DECIMAL: make .5 ticks shorter and 0.1 ticks even shorter
+    // Later: POINTY_KNOB : make the slider knob pointy on the side where the ticks are
+    // Later: SMALLE_KNOB : make the slider knob small, so the ticks are better visible
+  } Tick_Position;
+
+  /// Bitset for tick mark positions for Fl_Nice_Slider.
+  /// \see Fl_Slider::ticks(), Fl_Slider::ticks(Tick_Position)
+  typedef enum : uchar {
+    LINEAR_SCALE = 0,     ///< Linear scale (default)
+    LOG_SCALE             ///< Logarithmic scale
+  } Scale_Type;
+
+private:
+
   float slider_size_;
   uchar slider_;
+  Scale_Type scale_type_ { LINEAR_SCALE };
+  Tick_Position ticks_ { TICKS_NONE };
+  uchar num_ticks_ { 11 };
   void _Fl_Slider();
-  void draw_bg(int, int, int, int);
+  void draw_bg(int, int, int, int, int S=16);
 
 protected:
 
@@ -69,6 +99,9 @@ protected:
   void draw(int, int, int, int);
   int handle(int, int, int, int, int);
   void draw() override;
+  void draw_ticks(const Fl_Rect& r, int S);
+  double value_to_position(double val) const;
+  double position_to_value(double pos) const;
 
 public:
 
@@ -100,6 +133,34 @@ public:
 
   /** Sets the slider box type. */
   void slider(Fl_Boxtype c) {slider_ = (uchar)c;}
+
+  /** Gets the scale type.
+    \return scale type
+   */
+  Scale_Type scale() const { return scale_type_; }
+
+  /** Sets the scale type.
+    \param[in] s scale type
+   */
+  void scale(Scale_Type s) { scale_type_ = s; }
+
+  /** Gets the tick mark position.
+    \return tick mark position bitset
+  */
+  uchar ticks() const { return ticks_; }
+
+  /** Gets the number of tick marks.
+    \return number of tick marks
+  */
+  uchar num_ticks() const { return num_ticks_; }
+
+  /** Sets the tick mark position for Fl_Nice_Slider.
+   FL_TICKS_BELOW and FL_TICKS_ABOVE can be or'd together for horizontal sliders,
+   and FL_TICKS_LEFT and FL_TICKS_RIGHT for vertical sliders.
+   \param[in] t tick mark position bitset
+   \param[in] num_ticks number of tick marks to draw
+  */
+  void ticks(uchar t, uchar num_ticks=11) { ticks_ = (Tick_Position)t; num_ticks_ = num_ticks; }
 };
 
 #endif
-- 
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